@echo off

set "str=123456789"

echo String empty check
if not %str% == "" (
	echo str is not null
) else (
	echo str is null
)
pause

echo Read SubString from 3
set substr=%str:~3%
echo %substr%
pause

echo Read SubString from 3 length 5
set substr=%str:~3,5%
echo %substr%
pause

echo Read SubString from -7 length 5
set substr=%str:~-7,5%
echo %substr%
pause
